The long term goal of this project is to understand the neural basis of functional recovery after focal brain injury. Neuroimaging (functional magnetic resonance imaging, fMRI, and positron emission tomography, PET) and methods will be used to study the recovery of aphasia after focal damage to the left frontal lobe. In particular, we will assess the relative contribution to recovery of tissue surrounding the infarction, and/or of homologous regions in the contralateral hemisphere. These findings will have implications for the design of neurobiologically- oriented strategies of rehabilitation, and the evaluation of therapies aimed at salvaging brain tissue around the core of a stroke.